The present invention relates to an optical coupling module for transmitting/receiving an optical signal between optical fibers.
A conventional optical coupling module optically connects optical fibers to each other through lenses. In such an optical coupling module, assume that the optical axis is defined as the Z-axis, that an axis perpendicularly intersecting the optical axis is defined as the X-axis, and that an axis perpendicularly intersecting the optical axis and X-axis is defined as the Y-axis. Lens adjustment is performed in the X- and Y-axis directions perpendicular to the optical axis, and optical fiber adjustment is performed in the direction of optical axis (Z-axis direction) and the X- and Y-axis directions. For example, "Compact and All Resin-Free Polarization-Independent Optical Isolator", PROCEEDINGS OF THE 1993 IEICE AUTUMN CONFERENCE, pp. 4-296, 1993, C-216 describes an optical isolator using such an optical coupling module.
FIG. 5 shows a conventional optical coupling module. In the conventional optical coupling module, a ferrule 410 is mounted on one end portion of an optical fiber 401, as shown in FIG. 5. The ferrule 410 is mounted on one end of a cylindrical metal lens support 406 through a fiber support 408. A lens 403 is fixed in the lens support 406. An end face of the lens support 406 on a side opposite to the optical fiber 401 is connected to one end face of a cylindrical main body 405.
A ferrule 411 is mounted on one end portion of an optical fiber 402. The ferrule 411 is mounted on one end of a cylindrical metal lens support 407 through a fiber support 409. A lens 404 is fixed in the lens support 407. An end face of the lens support 407 on a side opposite to the optical fiber 402 is connected to an end face of the cylindrical main body 405 on a side opposite to the lens support 406.
A method of manufacturing the conventional optical coupling module having the above arrangement will be described. In this description, assume that the optical axis of the end portion of the optical fiber 401 on the ferrule 410 side and the optical axis of the end portion of the optical fiber 402 on the ferrule 411 side are defined as Z-axis, that an axis perpendicularly intersecting the Z-axis is defined as the X-axis, and that an axis perpendicularly intersecting the Z- and X-axes is defined as the Y-axis.
In order to mount the lens support 406, having the lens 403 fixed therein, on the main body 405, the lens support 406 is adjusted in the X- and Y-axis directions with respect to the main body 405. Thereafter, the lens support 406 is fixed to the main body 405 with a YAG (Yttrium Aluminum Garnet) laser or the like.
The ferrule 410 mounted on the optical fiber 401 is adjusted in the X-, Y-, and Z-axis directions, and is mounted on the lens support 406 through the fiber support 408. The lens support 407 and ferrule 411 are mounted on the main body 405 in a similar manner.
Since the conventional optical coupling module has a large number of components, it has many portions that need adjustment, and it takes a long period of time to adjust the optical coupling module. For automatic adjustment of the optical coupling module, since the number of portions that need adjustment is large, the algorithm becomes complicated, and it is difficult to automate adjustment.
In the conventional optical coupling module, the lenses 403 and 404 and the optical fibers 401 and 402 are held/fixed in a plurality of cylindrical members. Accordingly, the number of components is large, and downsizing is difficult to perform.